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 Post subject: Vacuum pump switch
PostPosted: Tue May 06, 2014 3:40 pm 
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Joined: Wed Jan 01, 2014 9:15 pm
Posts: 91
What are you guys using to switch off your pumps (with hysteresis ideally) at target vacuum? I have an old wastegate actuator I thought about preloading with a sping and using it to trigger a micro switch but I'm concerned it will cycle on an off too quickly.

I finally got my hands on an industrial fridge compressor (for free!). I'm using an old propane tank for a reservior and just need to get the switching rigged to start using it.


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 Post subject: Re: Vacuum pump switch
PostPosted: Tue May 06, 2014 8:30 pm 
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Joined: Wed Nov 20, 2002 1:00 am
Posts: 879
Location: rhode island
http://www.veneersupplies.com/products/ ... 8-NPT.html


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 Post subject: Re: Vacuum pump switch
PostPosted: Wed May 07, 2014 3:11 am 
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Joined: Mon Jul 01, 2013 7:16 am
Posts: 274
Location: Perth, Australia
An old car vacuum advance with a bed spring. Cost $1.
But, you right, it does switch too often - only if the job not sealed. Would the above switch do the same?
I am using a one way valve on my vac table but the pumps seals are gone, I think.


The start-up for a big pump can be easy 15-20A. Hence, you'll need an relay for the above switch.
And a fuse.


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 Post subject: Re: Vacuum pump switch
PostPosted: Wed May 07, 2014 11:46 am 
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Joined: Sun Feb 12, 2006 8:16 pm
Posts: 352
Location: Kettle Point Ontario Canada
http://www.acpsales.com/VacuumSwitch.html adjustable so you can change depending on what you are vacuuming for a core

you would need a http://www.acpsales.com/Vacuum-Switch-Relay.html also to make it work right

terrie
www.jellyfishboards.com


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 Post subject: Re: Vacuum pump switch
PostPosted: Wed May 07, 2014 3:30 pm 
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Joined: Mon Jul 28, 2003 12:47 pm
Posts: 200
Location: Cascais, Portugal
I built one myself with a used pump, a vacuum gauge and some gardening supplies. Very cheap and works like a charm. Just connect between pump and bag and regulate the vacuum with the valve:

Image

Image

It works both as a vacuum and water reservoir when i'm sucking water out of boards before repair.


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 Post subject: Re: Vacuum pump switch
PostPosted: Thu May 08, 2014 3:43 pm 
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Joined: Wed Jan 01, 2014 9:15 pm
Posts: 91
Both of the above switches seem to have a "grace period" or hysteresis to allow the pressure to drop a bit before the pump cycles back on. Thanks for the replies.


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 Post subject: Re: Vacuum pump switch
PostPosted: Thu May 08, 2014 11:37 pm 
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Joined: Sun Feb 12, 2006 8:16 pm
Posts: 352
Location: Kettle Point Ontario Canada
yes the one I posted is adjustable and if you have no leaks or very very little leak you don't have to have the vacuum pump running all the time... just saves the life of the pump a bit.

terrie


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 Post subject: Re: Vacuum pump switch
PostPosted: Fri May 09, 2014 8:18 am 
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Joined: Sun Dec 15, 2002 1:00 am
Posts: 247
Location: Slovenia
I made quite a few boards in the past. I was using the normal home fridge compressor without any switch. Sometimes when using really slow hardener it operated for more than 48 hours without stopping, and it never let me down. The (-) pressure that this unit produces is quite impressive also. This only works for wood cores though, becouse there can not be to much pressure. With foam cores - it would crush them, so there you need something to control the vacuum.
Just my findings...
Greetings,
Jaros


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 Post subject: Re: Vacuum pump switch
PostPosted: Fri May 09, 2014 1:42 pm 
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Joined: Mon Jul 01, 2013 7:16 am
Posts: 274
Location: Perth, Australia
Yes Jaroš,

however, a fridge pump spits some oil into the atmosphere, no need to run it all the time.

They might be designed to run like that, but with increasing elec. bills, at.al I am very cautious about board building expenses:)


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 Post subject: Re: Vacuum pump switch
PostPosted: Fri May 09, 2014 6:28 pm 
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Joined: Wed Jan 01, 2014 9:15 pm
Posts: 91
I'm far more concerned about over compression than I am about continuous run-time, pump life, power, etc. I have an oil collector on the outlet along with two filters to try and keep the misting from venting to atmostphere.


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